U.S. Pat. No. 4,535,307 to Tsukii discloses a test fixture for characterizing electrical devices such as field effect transistors. The fixture includes a base portion comprising a holder for receiving a solid state device positioned on a substrate. Transmission line sections which may include a straight line or a serpentine line section mounted on a substrate with a ground plane layer are disposed adjacent to the solid state device under test, but on opposite sides thereof. Slideable tuning elements are attached to the top of the fixture to allow testing at various frequencies.
U.S. Pat. No. 4,697,143 to Lockwood et al discloses a wafer type probe for the measurement of electrical characteristics of small planar devices fabricated on semi-conductive or dielectric wafers. The probe is provided with metallic transmission lines mounted on a tapered alumina substrate, generally surrounded by microwave absorbing material. This material absorbs energy propagating along the probe ground, thereby preventing the energy from resonating, radiating, or reexciting normal transmission line modes with minimal transmission line mode residence along the ground probe.
U.S. Pat. No. 4,680,538 to Dalman et al is directed to a swept-frequency analyzer which is constructed of standard microwave passive components and a controlled frequency sweeper and is used to make both reflection and transmission measurements with only two power meters. The simplicity of this device is based on the use of a 180.degree. hybrid, or "magic-tee" waveguide device, and allows accurate point-by-point measurements of device coefficients over a broad frequency band.